Skid-steer loaders are small work vehicles equipped with hydraulically powered lift arms that jointly carry a bucket or other working tool at their forward ends. An operator station or enclosure is carried in the middle portion of the loader.
Beneath the operator enclosure are housed loader components such as a hydrostatic transmission, steering linkages, hydraulic lines and valves for powering the lift arms, bucket, and auxiliary functions, hydraulic lines for the wheel motor drives and miscellaneous electrical wiring harnesses and connections. To permit access to these loader components for maintenance and related services, the operator enclosure must be moved. Common methods of moving it include sliding it forward, pivotally swinging it forward, and pivotally swinging it rearwardly.
Since the lift arms of a skid-steer loader extend along its sides, they can block access to the components. Front access is therefore often preferred. When forwardly sliding or forwardly swinging operator enclosures are provided on loaders, front access is precluded and the lift arms must be raised to permit access from the sides of the loader. When the loader hydraulic power system is not operable, the arms cannot be easily raised and working access can become difficult. To overcome this problem, some skid-steer loaders have been equipped with rearwardly swinging enclosures.
It is often desirable to equip skid-steer loaders with lift arms that raise vertically so that the vertical height and forward reach of the bucket is maximized and it is easier to empty the loader bucket into a truck. When such lift arms are provided on a skid-steer loader, both the forward and rearward ends of the arms are mounted to raise vertically and move the bucket along a substantially vertical path. To facilitate vertical movement of the arms, their rear portions are pivotally connected to links that allow the rearward ends of the arms to raise vertically relative to the loader. These links are sometimes mounted on vertically raised frame structures on the loader to increase the vertical reach of the arms. Because the links also permit swinging movement of the arms, the arms can be extended forwardly when raised to improve the ability to empty a load over the sides of a dump truck.
Since the raised frame structures must support the lift arms as well as the bucket and its load, they are sometimes reinforced with one or more cross members. Further, the links which support the lift arms are often reinforced with one or more transversely extending cross members. Either or both of these cross members can provide an obstacle to swinging an operator enclosure rearwardly and can severely restrict the degree to which it can swing upwardly and rearwardly. Accordingly, the available working area beneath the rearwardly raised operator enclosure, wherein maintenance on the vehicle components can be performed, can be restricted.
It would therefore be desirable to provide a skid-steer loader having an operator enclosure which can be moved upwardly and rearwardly to access the working components from the front of the vehicle. It would also be desirable to provide such an operator enclosure on a loader having links between the loader and rear end portions of the lift arms to provide vertically lifting arms.
It would further be desirable to provide support posts for mounting the lift arm links to enable the arms to raise above the loader frame and maximize their vertical height and forward reach for dumping loads over the sides of a dump truck.
Also, it would be desirable to provide a reinforcing cross member to stabilize the links and posts as well as permit the use of less substantial support structures for the posts.
It would further be desirable to mount the operator enclosure such that the bottom and back portions of the enclosure raise up and above the access or working area, and are not restricted in their upwardly and rearwardly movement by the cross member.
It would also be desirable to minimize the bulk of the operator enclosure, particularly the size of the frame components required in its construction.
And it would be desirable to provide a power means for raising the operator enclosure that will function when the loader's hydraulic or electrical power systems is down as well as one which is releasably lockable to secure the enclosure in its raised position.